The present invention relates to the field of optical elements and more particularly to the assembly and disassembly of optical elements.
It is desirable to provide an easy means of repeatedly disassembling or segmenting and reassembling components of a large optical element which is thus made highly portable and can be readily carried by one person from place to place. In order to enable this portability, the optical device should also be light and highly compact after being disassembled so as to be carried by the person to render it "man-packable".
One example would utilize the large optical element such as a lens or mirror, as the objective of a large collapsible telescope. The telescope body itself could also be collapsible thus allowing for a very lightweight, easily transportable telescope having a substantial size when reassembled. It is thus desirable to replace, for example, an eighteen inch diameter conventional cassegrain reflector system which can not be collapsed and which can weigh fifty pounds or more, with such a lightweight, collapsible and portable reflector system to render the telescope portable. The resulting telescope could thus weigh only a few pounds and be sufficiently compact to be backpack-transportable.
It is also desirable to provide a collapsible, lightweight, portable optical "antenna" for use with a field transportable laser beam communication receiver. The best way to improve receiver gain is to collect more of the incoming laser beam signal energy by employing a larger optical collector or "antenna". It would also be desirable to provide a readily transportable solar energy collector for power generation in the field. The electrical power generated would be useful for energizing remote radio transmitters or other instruments in the field, in support of scientific experiments or for military applications. A lightweight, collapsible optical "antenna" or solar energy collector would also have numerous applications in space for use on satellites etc.
In the above applications, it would be most desirable to employ some type of flat, light-weight optic such as a plastic fresnel lens. A simple fresnel lens could satisfy most of the aforesaid applications. However, due to their generally poor imaging capability, fresnel lenses should mainly be used for optical energy collection, such as "antennas" for optical communications and lidar systems or as solar power concentrators. High quality imaging can best be accomplished with diffractive or binary optical elements. Although essentially the same in size and general appearance as a fresnel lens, these elements have a much denser groove spacing and provide for near diffraction-limited performance which is comparable to or better than a basic curved lens or mirror. The only potential problem with using a diffractive optic as the major light gathering element of a telescope is its optical wavelength sensitivity which can cause chromatic distortion when used with broadband light sources such as white light. However, recent independent developments in diffractive optics technology have provided solutions to this problem via small corrective optical elements which can be incorporated in the light path. Thus a high performance imaging telescope which is light weight and collapsible could be implemented by the present invention.
Fresnel, diffractive and binary optical elements can be produced on a number of different substrates including glass, metals and plastics. Furthermore, they can be inexpensively molded by plastic injection or compression molding from a master copy. Fabrication from a reflective material produces a mirror. A mirror can also be produced by providing an appropriate reflective coating on a transmissive optic. Use of the optic in the present invention can be accomplished by producing the segments as separate units, or simply by cutting the optical element into separate sections after its fabrication.